Gel-filled blood pressure transducer

Abstract

A reusable pressure transducer for use with a detachable dome. The pressure transducer includes a body having a recess with an opening covered by a flexible diaphragm. The body has a hole opposite the flexible diaphragm and a sensor placed over the hole. A dielectric gel fills the recess to transmit to the sensor variations in pressure imparted to the diaphragm.

We claim: 
     
       1. A reusable pressure transducer comprising: a body having a recess terminating in an opening surrounded by a rim, said body having an outer surface;   a flexible diaphragm placed over said rim to enclose said recess;   said body having a hole spaced from said diaphragm, said hole connecting the outer surface of said body to said recess;   a pressure sensor mounted on said outer surface over said hole;   and a dielectric gel completely filling said recess and hole and in contact with both said diaphragm and said pressure sensor whereby pressure on said diaphragm will be communicated through said gel to said sensor, said dielectric gel slightly distending said diaphragm.   
     
     
       2. A reusable pressure transducer as in claim 1 in which said gel is cured in said recess from two parts that are mixed together: one of said parts is polydimethylsiloxane and a catalyst, and the other of said parts is polydimethylsiloxane with a hydrogen cross linker.   
     
     
       3. The method of making a transducer comprising the steps of: forming a body with a cavity opening at one side and a first bore extending from said cavity to another side of said body;   forming a filling bore to said cavity;   enclosing said opening with a flexible diaphragm;   mounting a sensor assembly over said first bore;   filling said cavity with a curable liquid through said filling bore;   plugging said filling bore, the quantity of liquid in said cavity distending said diaphragm upon plugging of said filling bore; and   curing said liquid to form a gel.   
     
     
       4. The method as in claim 3 further comprising the steps of: mixing said curable liquid in a vacuum;   filling said cavity with said liquid while said cavity is in a vacuum.   
     
     
       5. The method as in claim 4 in which one part of said gel is polydimethylsiloxane and a platinum catalyst and the other part is polydimethylsiloxane with a hydrogen cross linker. 
     
     
       6. The method as in claim 3 in which said gel has a Universal Penetrometer penetration of about 3.0 -9.0 mm using a 19.5 gram shaft with a 1/4 inch diameter foot.